std::out_of_range在字符串向量中搜索匹配项时发生异常

Question

在我的C++程序中，我有一个文本文件，我逐行读取到一个名为flights的vector中，然后在这个字符串向量中搜索一些字符串，但不幸的是，如果我找不到任何匹配项，我会得到以下错误

飞行矢量的格式如下：

EMA CDG BritishAirways 120 100
CDG VIE AirFrance 120 100
EMA VIE BritishAirways 150 300
EMA CDG AirFance 130 80
GRO FFF Rayanair 130 80
FFF HHH AirItalia 100 50

OOP项目中0x769E4598处的未处理异常。exe：内存位置0x0052F0F0处的Microsoft C++异常：std:：out_of_range。

我想我已经发现错误一定在我的connectedJourney函数中的某个地方：

/*  The following code searches for journeys that have a connection. so the use 2 different flights
First of all looks for flights that are leaving from the same airport that the user indicated and stores the flight details in "deptMatches". 
Secondly it will look for flights that have the destination that the user indicated and stores it in "destMatches". 
Thirdly it will check if the destination code of any of the deptMatches matches the departure code of any of the destMatches.*/
vector < vector < string >> connectedJourney(string airpCode1, string airpCode2, vector < string > flights) {
  vector < vector < string >> rawMatches;
  vector < string > deptMatches;
  for (unsigned int f1 = 0; f1 < flights.size(); f1++) {
    //store all the fligths that match the departure airport into deptMatches
    if (airpCode1 == flights[f1].substr(0, 3)) {
      deptMatches.push_back(flights[f1]);
    }
  }
  vector < string > destMatches;
  for (unsigned int f2 = 0; f2 < flights.size(); f2++) {
    //store all the fligths that match the departure airport into deptMatches
    if (airpCode2 == flights[f2].substr(4, 3)) { //the call stack says the error is at this line 
      destMatches.push_back(flights[f2]);
    }
  }
  if (deptMatches.size() == 0 || destMatches.size() == 0) {
    // check if there won't be any matches
    throw noEntryFound();
  } else {
    vector < string > cj_Matches; //connected journey matches
    for (unsigned int g1 = 0; g1 < deptMatches.size(); g1++) {
      for (unsigned int g2 = 0; g2 < destMatches.size(); g2++) {
        if (deptMatches[g1].substr(4, 3) == destMatches[g2].substr(0, 3)) {
          //if the arrival place of the first flight matches the departure place of the first flight then the details of both flights are saved into a vector within another
          rawMatches[0].push_back(deptMatches[g1]);
          rawMatches[1].push_back(deptMatches[g2]);
        }
      }
    }
    return rawMatches;
  }
}

如果有用的话，我也在这里上传了我的整个项目：https://drive.google.com/folderview?id=0B-VbnRtajCWIfmFxMk5UUncwSkNzNm8tT2xrU0hDM29kbzg4TUFKODJSUExMTV9oVDFncjA&usp=共享

Answer 1

试试这个：

  for (unsigned int f2 = 0; f2 < flights.size(); f2++) {
     //store all the fligths that match the departure airport into deptMatches
     string code = flights[f2];
     if (code.length() > 7 && airpCode2 == flights[f2].substr(4, 3)) { //the call stack says the error is at this line 
    destMatches.push_back(flights[f2]);
     }
  }

这就是我会做的：

   vector<string>::iterator iter = flights.begin(); 
   for (; iter!=flights.end(); ++iter) {
      istringstream is(*iter);
      string tokens[5];
      for (unsigned int i=0; i<5; ++i) {
     is >> tokens[i];
      }
      if (tokens[0] == airpCode1) {
     deptMatches.push_back(*iter);
      }
      if (tokens[1] == airpCode2) {
     destMatches.push_back(*iter);
      }
   }

Answer 2

您应该查找"传递闭包"和Warshall的算法。我想我下面的代码可以做你想做的事情。

#include <string>
#include <iostream>
#include <set>
#include <vector>
#include <sstream>
#include <stdexcept>
// if you prefer to 'weight' your search on time
// uncomment time and comment price
#define PRICE
//#define TIME
using namespace std;
static const size_t NUMFLIGHTS=6;
static const char* data[] {
   "EMA CDG BritishAirways 120 100",
      "CDG VIE AirFrance 120 100",
      "EMA VIE BritishAirways 150 300",
      "EMA CDG AirFance 130 80",
      "GRO FFF Rayanair 130 80",
      "FFF HHH AirItalia 100 50"};
struct flight {
   void set(const string& input) {
      istringstream is(input);
      is >> dept >> dest >> airways >> time >> price;
   }
   string dept;
   string dest;
   string airways;
   unsigned int time;
   unsigned int price;
};
struct travelData {
   travelData() : weight(0), infinity(true) {}
   vector<flight> flights;
   unsigned int weight;
   bool infinity;
   void print() {
      auto i=flights.begin();
      for (;i!=flights.end(); ++i) {
     cout << i->dept << " " << i->dest << endl;
      }
      cout << weight << endl;
   }
};
struct database {
   vector< vector<travelData> > allflights;
   flight flights[NUMFLIGHTS];
   vector<string> locations;
};

travelData FlightExists(const flight* flights, const string& dept, const string& dest) {
   travelData ret;
   for (size_t i=0; i<NUMFLIGHTS; ++i) {
      if (flights[i].dest == dest && flights[i].dept == dept) {
     ret.flights.push_back(flights[i]);
#ifdef PRICE
     ret.weight = flights[i].price;
#elif LENGTH
     ret.weight = flights[i].time;
#else
     ret.weight = 1;
#endif
     ret.infinity= false;
     return ret;
      }
   }
   return ret;
}

database setup()
{
   database ret;
   set<string> locationsSet;
   for (size_t i=0; i<NUMFLIGHTS; ++i) {
      ret.flights[i].set(data[i]);
      locationsSet.insert(ret.flights[i].dept);
      locationsSet.insert(ret.flights[i].dest);
   }
   copy(locationsSet.begin(), locationsSet.end(), back_inserter(ret.locations));
   size_t len = ret.locations.size();
   for (size_t i=0; i<len; ++i) {
      string searchDept = ret.locations[i];
      vector<travelData> row;
      for (size_t j=0; j<len; ++j) {
     string searchDest = ret.locations[j];
     if (i == j) {
        travelData blank;
        blank.infinity = false;
        row.push_back(blank);
     } else {
        row.push_back(FlightExists(ret.flights, searchDept, searchDest));
     }
      }
      ret.allflights.push_back(row);
   }
   // Warshalls algorithn
   for (size_t k=0; k<len; ++k) {
      for (size_t i=0; i<len; ++i) {
     for (size_t j=0; j<len; ++j) {
        travelData& d = ret.allflights[i][j];
        travelData& s1 = ret.allflights[i][k];
        travelData& s2 = ret.allflights[k][j];
        if (!s1.infinity && !s2.infinity) {
           int sum = s1.weight + s2.weight;
           if (d.infinity) {
          d.infinity = false;
          d.flights.insert(d.flights.begin(), 
                   s1.flights.begin(), 
                   s1.flights.end());
          d.flights.insert(d.flights.begin(), 
                   s2.flights.begin(), 
                   s2.flights.end());
          d.weight = sum;
           } else if (d.weight > sum) {
          d.flights.clear();
          d.flights.insert(d.flights.begin(), 
                   s1.flights.begin(), 
                   s1.flights.end());
          d.flights.insert(d.flights.begin(), 
                   s2.flights.begin(), 
                   s2.flights.end());
          d.weight = sum;
           }
        }
     }
      }
   }

   return ret;

}
size_t GetIndex(const database& db, const string search) {
   size_t len = db.locations.size();
   for (size_t i=0; i<len; ++i) {
      if (db.locations[i] == search) {
     return i;
      }
   }
   throw runtime_error("bogus search");
}
travelData GetResults(const database& db, const string& dept, const string& dest) {
   travelData ret;
   size_t i_index = GetIndex(db, dept);
   size_t j_index = GetIndex(db, dest);
   return db.allflights[i_index][j_index];
}
int main() {
   database db = setup();
   travelData result = GetResults(db, "GRO", "HHH");
   result.print();
   return 0;
}